4 x DIMM, Max. 32GB, DDR3 2133(O.C.)/1866/1600/1333/1066 MHz ECC, Non-ECC, Un-buffered Memory Dual Channel Memory Architecture * Refer to www.asus.com or user manual for the Memory QVL (Qualified Vendors Lists). * Due to OS limitation, when installing total memory of 4GB capacity or more, Windows® 32-bit operation system may only recognize less than 3GB. Install a 64-bit Windows® OS when you want to install 4GB or more memory on the motherboard. * Due to CPU spec., AMD 100 series CPUs support up to DDR3 1066MHz. With ASUS design, this motherboard can support up to DDR3 1333MHz.